RD-861 is missing in game

This hypergolic engine was used as the third stage on Tsyklon 2 and 3, a later RD-861K version was intended to power the third stage of Tsyklon 4 and 4m too if i understand correctly.
https://www.russianspaceweb.com/rd861k.html
https://en.wikipedia.org/wiki/RD-861
the engine doesnt look to different from S1.5400 so i guess that model could be used as a placeholder till someone makes a better one.